Carrier telegraph system



Sept. 22, 1925. 1,554,290

R. D. PARKER ET AL CARRIER TELEGRAPH SYSTEM Filed May a, 1920 INVENTORS A TTQRNEY Patented Sept. 22, 1925.

UNITED STATES.

PATENT OFFICE.

RALZEMOND D. PARKER AND BAXTER P. HAMTLTON, F BROOKLYN/NEW YORK, AS-

SIGNORS T0 AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

panama TELEGRAPH SYSTEM. 1

' Application filed May 8,

To all whom it may concern:

Be it known that we, Ranzrnsrom) D. PARKER and BAXTEB P. HAMILTON, residing at Brookl n, in thecounty of Kings and 5 State of ew York, respectively, have invented certain Improvements in Carrier 7 Telegraph System's, .of-which the following is a specification. g This invention relates to telegraph sys- 10 tems, and more particularly to telegraph sytemsin which alternating currents are emplo ed for transmission purposes.

(l ne of the objects of the invention is to provide a telegraph system in which alternating carrier-currents are used for transmission purposes, instead of direct currents.

Another object of the invention is toprovide a telegraph system in which currents of one frequency are used for transmitting marking impulses and currents of another frequency for transmitting-spacing impulses.

v Another object of the invention is to pro-' vide a system in which Weather changes, changes in the voltage of the batteries associated with the detector, and other similar \changes, produce substantially no change in the bias of the signals.

'Other and further objects of the invention will more fully appear from the following description when read in connection with the accompanying drawing, the figure of which illustrates one form of the. invention.

Referring to the drawing, L designates a transmission circuit such as an ordinary tele,-

phone line. The line L may be composited in the well known manner for the transmis sion of Morse signals by means of the composite set (3,, schematically indicated in the 40 drawing. For making telephone connections the line L terminates-fin a jack J. Where it is desired to use the telephone line L as a v circuit for the transmission of carrier currents a branchL" may be provided, and in 4 order to separate the earner frequencies iwlth the receiv ng channel RL com rises from the ordinary telephonic frequencies, filters F and F are included in the branch L leading" to, the jack J and the carrier branch L" respectively. These filters ma be of the general t pe illustrated in the U. Patent'issued to eorge A. Campbell 1,227, 113,'dated May 22, 1917. The filter F is desi ed to transmit currents within the telep one range while excluding currents of 1920.\ Serial No. 379,964.

higher or lower frequency depending upon whether the carrier current channels are above or below the telephone range. The filter F on the other hand, is designed to transmit currents within the carrier range and to suppress currents of telephonic frequency. If the carrier currents are above the telephonic range the filter F" may be vacuum tube oscillators of well known type.

The oscillators generate currents of different frequencies," the oscillator 0 generating a frequency used for a spacing signahand the oscillator 0 generating a frequency which is used for the marking signal. These oscillators are' associated through tunedcircuits 11 and 12 with the transmitting circuit TL. A transmitting relay TR is provided for controlling the transmission of the marking and spacing frequencies, the

armatureof said relay being so arranged that when in one position a circuit will be closed rendering the oscillator 0 actlve and when in the other position a circuit will be closed renderin the oscillator 0 active. As illustrate when the relay TR is energized, the circuit of the oscillator 0 is closed so that the marking frequencyis transmitted and when the transmitting circuit DR is de-energiaod, the oscillator 0 is rendered active to transmit the spacing frequency.

The carrier receiving apparatus associated two detectors D and D which may e of any well known type, but are preferably detectors of the well known vacuum tube or audion type, which, as is well known, control by means of a grid the flow of current in an output circuit including a so-called B battery. These detectors are connected by means of tuned circuits 11 and 12' to the receiving channel BL, and include in their output circuits separate windings of a polar relay PR. The armature of the polar relay is shifted to the lower position in response to the spacing frequency and to the upper position in response to the marking fre uency.

'l he operation is as follows: As the transmitting relay TB is operated, its armature operates between the contacts 1 and 2 to alternately render the oscillators O and 0 active, thereby alternately transmitting spacing and marking frequencies to the en'- cuit TL. These frequencies are transmitted to the midpoints of the windings of the transformer 10, and due to the balanced relation of the circuit are substantially without effect upon the local receiving circuit RL, the energy of the two frequencies being divided between the network N and the circuit L, so that signaling currents of the marking and spacing frequencies are transmitted from the circuit L over the line L to operate receiving apparatus at the distant station. Similar marking and spacing frequencies transmitted over the line L from the distant station pass into the circuit L through the filter F and are transmitted through transformer 11 to the receiving circuit RL. Currents of spacing frequency are selected by the tuned circuit 11, and act upon the detector D to cause a pulse of current to flow through lower winding of the polarrelay PR so that its armature is shifted to the spacing .contact. When currents of marking frequencies are received the are selected by the tuned circuit 12' an act upon the detector 1), to produce a pulse of current in the upper winding ofthe polar relay PR thereby shifting its armature to the mark ng contact.

It will be obvious that the general principles herein disclosed may be embodied in many other organizations widely. different from those illustrated, without departing from the spirit of the invention, as defined in the following claims.

What is claimed is: p

1. In a telegraph system, a transmission circuit, receiving apparatus associated therewith, said receiving apparatus including a current responsive relay andits armature,- and means responsive to currents of one frequency only to produce energy to shift said armature in one direction to register a marking signal, and means responsive to currents of another frequency only produce ener y to shift said armature 1n the opposite lrection to register a spacing signal. i

2. In a telegraph system, a transmission circuit, a telegraph transmitter and a receiver associated with said line, said receiver including a current responsive relay and its armature, means controlled by said transmitter for transmitting currents of one frequency only in response to a marking signal, and means fortransmitting currents of another frequency only in response to a spacing signal, means associated with said receiver and operating in response to the currents of spacing frequency to produce energy to shift said armature in one direction to register a marking impulse, and means responsive to currents of spacing frequency to produce energy to shift said armature in the opposite direction to register a spacing signal.

3. In a telegraph system, a transmission circuit, a transmitting channel and a receiving channel associated with said line in such a manner as to be substantially conjugate with respect to each other, a transmitting apparatus associated with the transmitting channel and comprising means for transmitting one frequency only for marking signals and another frequency only for a spacing signal, and a recelvin apparatus associated with said receiving 0 annel, said receiving apparatus including a current responsive relay and its armature, said receiving apparatus comprising means responsive to one frequency to produce energy to shift said armature in one direction for registering a marking signal and responsive to another frequency to produce energy to shift said armature in the opposite direction for registering a spacing signal.

4. In a telegraph system, a transmission circuit, a telegraph transmitter and a telegraph receiver associated therewith, a pair of oscillators controlled by said telegraph transmitter, one of the said oscillators being rendered active to supply currents of one frequency only to the transmission line in response to a marking signal, and the other oscillator being rendered active by said transmitter to supply currents of another frequency only to the transmission line in response to a spacing signal, and'a pair of detectors associated with said telegraph receiver, one of said: detectors being responsive to currents of marking frequency to actuate said receiver to register a marking impulse, and the other detector being responsive to currents of spacing frequencv to actuate said receiver to register a spacing impulse. a

In testimony whereof, we have signed our names to this specification this 7th day of May 1920. RALZEMON'D D. PARKER. BAXTER P. HAMILTON 

